Why are the best index fossils from species that only existed for a short period of time ?

Answers

Answer 1

Answer:

Because once they were very common they disappeared after the mass extinction event. ... Many geologic periods were defined by events that made natural boundary to the period.

Answer 2

Answer: Because once they were very common they disappeared after the mass extinction event.

Explanation: Hope this helppssss!!! :)


Related Questions

If RNA strand reads AUG CGU AAU UAU, what did its source DNA read?

Answers

Answer:

TAC GCA TTA ATA

and apparently my answer needs to be 20 charcters long

define the term area opaca and area pellucide

Answers

Answer:

Explanatiothe peripheral opaque area that surrounds the area pellucida of a vertebrate embryo (as of a bird) formed by discoidal cleavage.

PLEASE HELP I WILL GIVE BRAINALIST AND EXTRA POINTS

Answers

Answer:

Coal-fired power plants

Explanation:

Generally speaking coal-fired power plants emit more greenhouse gas, however both emit greenhouse gases in large quantities.

Water that is trapped within the Earth is called

Answers

Answer:

ringwoodite

Explanation:

smarty

Answer:

I think, its ringwoodite

What is the source of the carbon dioxide that is used in photosynthesis?

A. sunlight
B. the soil
C. the atmosphere
D. the plant

Answers

Answer:

A

Explanation:

Sunlight provides the energy needed for photosynthesis to take place.

45. If we put ANY type of cell in pure water: a) is pure water considered hypotonic, hypertonic or isotonic? b) would the cell shrivel or swell? c) what would happen to its turgor pressure (water pressure inside cell): increase or decrease?

Answers

Answer:

Explanation:

Pure water is an hypotonic solution that allows for diffusion of water into the cell and the cell will begin to swell.

The movement of water into the cell will make the cell swell but if water is moving outside the cell will collapse and shrink.

The turgor pressure is usually found withing the cell it ensures the movement of solutes when water is taken into the cell, the turgor pressure will increase. When water is taken out of the cell, the pressure will reduce.

How does the body protect itself from the majority of pathogens it encounters?

Answers

Answer:

In general, your body fights disease by keeping things out of your body that are foreign. Your primary defense against pathogenic germs are physical barriers like your skin. You also produce pathogen-destroying chemicals, like lysozyme, found on parts of your body without skin, including your tears and mucus membranes. In response to infection, your immune system springs into action. White blood cells, antibodies, and other mechanisms go to work to rid your body of the foreign invader. The immune system has a vital role: It protects your body from harmful substances, germs and cell changes that could make you ill. It is made up of various organs, cells and proteins.

Once infected cells have sensed an invading pathogen, they secrete molecules called cytokines and chemokines. These cells are then primed to resist an infection with the invading virus. Cytokines such as interferons activate anti-viral genes in the infected and neighbouring cells.

Microorganisms capable of causing disease—or pathogens—usually enter our bodies through the eyes, mouth, nose, or urogenital openings, or through wounds or bites that breach the skin barrier. Organisms can spread, or be transmitted, by several routes.

The second line of defense is nonspecific resistance that destroys invaders in a generalized way without targeting specific individuals: Phagocytic cells ingest and destroy all microbes that pass into body tissues. For example macrophages are cells derived from monocytes (a type of white blood cell).

If pathogens do manage to enter the body, the body's second line of defense attacks them. The second line of defense includes inflammation, phagocytosis, and fever.

Answer:

your skin protects itself because of all the oils on your glands .. but when you get a cut the while blood cells trap and eat them

Explanation:

what is the cell doing when it's not going through mitosis

Answers

when they’re not actively undergoing mitosis, they’re undergoing interphase where the chromosomes copies itself in the nucleus. so basically, they’re preparing for mitosis

Some can force their stomachs outside their mouths to digest prey
A. Sea stars
B. Sea urchins
C. Snails
D. Slugs

Answers

Answer:

A. Sea stars

Explanation:

Answer:

sea star

Explanation:

egn

Select the correct answer. What falls in the gray area between living and nonliving things? A bacteria B. mold C. virus D. yeast Reset​

Answers

Answer: C Virus

Explanation:

Why is it virus?, you may ask. Well... virus falls on the grey area between non living and living things

What is a Metamorphic Rock?

rock that forms when existing rock changes to a new rock because of heat and pressure


rock that forms by the process of compaction and cementation of sediments


rock that forms when melted rock (magma, lava) cools and hardens


pls help

Answers

Answer: A) rock that forms when existing rock changes to a new rock because of heat and pressure ..hope this helped!

Explanation:

____is a teratogen

BPA
Formaldehyde
Ultraviolet radiation
Alcohol

Answers

Answer:

Alcohol is a treatogen.

Certain chemicals, social drugs and some medicine are also some examples of treatogen.

It would be alcohol

In the 1520s, the Spanish explorer Cortes and his armies carried the virus that causes smallpox to NorthAmerica and South America.
The graphs above illustrate the death rate among both Europeans and American Indians from smallpox at that time. Which of the following statements best explains the difference in death rates?

F. People in Europe were healthier than American Indians.

G. Antibiotics were available in Europe but not in North America.

H. American Indians had never been exposed to the smallpox virus, so resistant individuals had not yet become common.

J. American Indians were exposed to a virus that was different from the virus for smallpox in Europe.

Answers

Answer:

I can't see the graph but I believe that the answer is H

List the cell organelles involved in energy generation for the cell.

Answers

Answer:

Mitochondria are tiny organelles inside cells that are involved in releasing energy from food. This process is known as cellular respiration. It is for this reason that mitochondria are often referred to as the powerhouses of the cell.

The cohesion-tension theory proposes that the physical properties of water allow the rise of water through a plant. Sketch and describe cohesion and adhesion of water molecules. Don't do the sketch part only do just the description part.

Answers

Answer:

Cohesion: the attraction force between the same type of molecules.

Adhesion: the attraction force between different types of molecules.

Answer: Which of the following is formed from lava whose chemical composition is similar to that of both light-colored and dark- colored lava?
a. rhyolite
b. pumice
c. andesite
d. basalt​

Answers

Answer:

My answer would be, d. basalt just from my learning. Hope this helps!!

Explanation:

If an organism's diploid number is 14. its haploid number is...​

Answers

Answer:

If an organism's diploid number is 14. its haploid number is...

Explanation:

Answer:

7

Explanation:

14 ÷ 2

a haploid is half the diploid

so the answer is 7

What do variations create?

Answers

Variations in species help them to adapt themselves to that particular environment and give them a chance of survival. For example, thermophilic bacteria are variants that are resistant to extreme temperature. They have a chance of survival in high temperate zones while others die.

define cyclosis and plasmolysis​

Answers

Cytolysis. The rupturing of a cell due to excess internal pressure. Plasmolysis. Collapse of a walled cell's cytoplasm due to a lack of water.

Answer:

Cyclosis- streaming of cytoplasm within a living cell without deformation of the external cell membrane. In some plant cells there is a rapid rotatory cytoplasmic movement, which is limited to the peripheral parts of the cell next to the cell wall; chloroplasts and granules move in this stream.

Plasmolysis is the process of shrinkage or contraction of the protoplasm of a plant cell as a result of loss of water from the cell. Plasmolysis is one of the results of osmosis and occurs very rarely in nature, but it happens in some extreme conditions.

Explanation:


Describe the movement of water if cells are in a hypertonic solution, hypotonic solution, and isotonic solution.
Why?

Answers

Water molecules move inside the cell in a hypotonic solution causing it to swell


Water molecules move outside the cell in a hypertonic solution causing it to shrink


Water molecules in an isotonic solution does not move inside or outside the cell and the cell’s volume will remain stable

Please help meeeeeeeeeeeeeeeeeeeeeeeeeee

Answers

Answer:

1.) The two gametes found in humans are the sperm and the ova.

2.) Variation, in biology, any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences (genotypic variation) or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation).

3.) Because the alleles that the mother and the father carry are mixed together in the offspring.

4.) Because it only introduces genetic variation into the population if a random mutation in the organism's DNA is passed on to the offspring.

Please this is all I can answer

list the types of infectious agents that may infect the human body

A. fungi, hookworms sore throats bugs
B. immune system diseases viruses fungi
C. infection sickness bacteria attackers
D. viruses bacteria, fungi, and parasites

Answers

Answer:

either a or d

Explanation:

ITS A my bad hope it works

Do you think phyiscal therapy is beneficial
for DMD patients? Why or Why not? ?
Biology

Answers

Answer:

The correct answer is - yes, physical therapy is beneficial for DMD patients.

Explanation:

Duchenne muscular dystrophy (DMD) is a condition that is inherited which affects the muscles, causing muscle weakness that occurs at a young age mostly from the age of four and worsens in a short time.

There is no known cure for this condition, however, to relieve the symptoms there are medicines such as steroids but for the daily routine work and provide movement physical therapy requires. The therapist helps them to do their maximum physical potential

Amino acid is to protein as

nucleotide is to nucleic acid
fat is to lipid.
DNA is to RNA.
sugar is to fat​

Answers

Fat is to lipid that is the answer because amino acid is organic compounds that combine to form proteins!

Name 2 ways that the Theory of evolution is currently being used to improve the quality of human life

Answers

Answer:

The answer to the question: Name two ways that the Theory of Evolution is currently being used to improve the quality of human life, would be: Through the development of evolutionary biology, and 2. Through the comprehension of how the systems of disease, and health, work.

Answer:

Through the development of evolutionary biology.And Through the comprehension of how the systems of disease, and health, work.

Canals such as the one shown in the image are artificial waterways built to allow the
movement of large ships that cannot travel along shallower, natural waterways.
Which of these is an advantage that a system of canals might bring to a city?

Answers

Answer:

b

Explanation:

What happens when sugar solution is filtered

Answers

Answer:

The water passes through the filter paper.

Explanation:

Since sugar is able to dissolve completely in water, sugar solution is a homogenous mixture and thus its composition is uniform throughout and is able to be filtered out without separating its components.

a farmer sprays his crops once a week with pesticides to kill beetles. he noticed that the pesticide he used last year is not killing the beetles this year . the beetles have evolved which strategies would best way to stop the evolution of pesticide resistant beetles?

Answers

The best way to stop is to use different forms of pesticide (stronger ones and then weaker ones). Or even use different form is terms of liquid or pebbles etc etc. This is because the beetles would not get used to one thing over and over again (natural selection) and hence stops the evolution.


help me please its due in a hour

Answers

Answer:

The correct answer is - in the sickle-cell hemoglobin is the replacement of glutamic acid with valine in the β-globin amino acid chain.

Explanation:

Sickle cell anemia has a mutant gene in which that produces has valine amino acid instead of glutamate in the hemoglobin protein. In the given question the structure of the protein has only one difference that is the replacement of the glutamic acid in normal hemoglobin to valine in the β-globin amino acid chain in the mutant protein.

Valine 6 (beta chain) binds to a different hydrophobic patch (on the alpha chain and causes the disease in sickle cell anemia cases.

Suppose the light converged before reaching the back of the eye.
What lenses would be in the person's glasses to help them see? Explain
your choice.

Answers

Answer:

z

Explanation:

If the light converges before reaching the back of the eye, this means that the person is nearsighted and has trouble seeing objects that are far away. To correct nearsightedness, the lenses in the person's glasses would need to divert the light before it entered the eye. Therefore, the glasses would have concave lenses.

what are lenses?

If the light converges before reaching the back of the eye, it means that the person is suffering from a refractive error known as myopia, or nearsightedness. To correct myopia, the lenses in the person's glasses should be concave, which means they are thicker at the edges and thinner in the center. Concave lenses are designed to diverge light rays, which helps shift the focal point of light farther back so that it falls directly on the retina. By doing so, the glasses help the eyes see distant objects more clearly.

Hence, if the light converges before reaching the back of the eye, this means that the person is nearsighted and has trouble seeing objects that are far away. To correct nearsightedness, the lenses in the person's glasses would need to divert the light before it entered the eye. Therefore, the glasses would have concave lenses.

Learn more about the lenses here.

https://brainly.com/question/15969013

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